<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h2>普通函数与箭头函数</h2>
</body>
<script>
    function getName() {

        console.log('hello getName')
        console.log('arguments',arguments)
    }
    new getName(1,2,3,4,4)

    let fn=()=>{
        console.log('hello fn')
        console.log('arguments222',arguments)
    }

    //new fn()
    //fn()
   console.log(this===window)
    var obj={
        username:'jack',
        getUserName:function() {
           let aaa=()=> {
               console.log('this',this)
              return this.username
            }

            aaa()
        }
    }

    obj.getUserName()

    let sum=(a,b)=>{


     //....


    //return 返回值

    }

    console.log(sum(20,10))


</script>
</html>